Capacitive Pressure Sensor Wearable for Spasticity Measurement
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Solution Overview
Problem
Current methods for assessing spasticity lack repeatable and objective metrics, leading to inadequate dosage of medications and severe side effects, with existing sensors being inconvenient and unable to detect subtle changes in hypertonicity effectively.
Innovation Solution
A hypertonicity measuring device comprising a wearable item with a sensor array of capacitive pressure sensors and an inertial measurement unit, capable of communicating data to a processing device for estimating power, and a patient simulation device for calibrating the system, which includes an adjustable friction generator and motion sensor to accurately measure spasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wearable devices and EMG sensors are deployed on patients to detect spasticity symptoms, then spasticity detection capability is improved, but patient comfort and convenience deteriorate
Solution Approach 1:
The patent employs a flexible pressure sensor array integrated into a wearable garment with thin film structure. The sensor array uses flexible printed circuit boards and thin encapsulation layers that conform to body contours, enabling spasticity detection while maintaining patient comfort through soft, breathable materials that do not restrict movement or cause discomfort during prolonged wear.
2Loss of information
If EMG sensors are used to detect muscle tone, then muscle tone characterization is improved, but measurement resolution for subtle hypertonicity changes deteriorates
Solution Approach 1:
The patent replaces EMG's electrical signal-based muscle detection with a mechanical pressure sensing system. The flexible pressure sensor array directly measures mechanical forces and torques during passive limb movement, providing high-resolution detection of subtle hypertonicity changes through capacitive sensing that captures minute force variations with femtofarad resolution, superior to EMG's indirect electrical signal measurement.
3Force
If force sensors are used to measure forces, then force measurement capability is improved, but measurement resolution for subtle hypertonicity changes and temperature stability deteriorate
Solution Approach 1:
The patent replaces traditional resistive force sensors with capacitive pressure sensors that measure force through changes in capacitance rather than electrical resistance. This substitution provides higher measurement resolution through femtofarad-level capacitance detection and eliminates temperature drift issues inherent in resistive sensors, as capacitive measurements are inherently more stable across temperature variations.
4Adaptability or versatility
If the modified Ashworth score is used to assess spasticity, then assessment capability is improved, but inter-rater reliability and sensitivity to changes deteriorate
Solution Approach 1:
The patent implements objective feedback through quantitative force and torque measurements captured by the pressure sensor array during standardized passive movement protocols. The system provides numerical data on muscle resistance, catch angle, and range of motion, replacing subjective visual assessment with measurable parameters that eliminate inter-rater variability and enable precise tracking of spasticity changes over time and in response to treatment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device provides a more accurate and comfortable means to assess spasticity, reducing inter-rater variability and enabling precise quantification of spasticity levels, improving treatment efficacy and patient safety.
Implementation Method 1
a sensor array, such that the sensor array is disposed to the at least one wearable item; including a plurality of capacitive pressure sensors
Implementation Method 2
an inertial measurement unit: disposed to the at least one wearable item; and configured to communicate motion data to the processing device
Implementation Method 3
a plurality of capacitive pressure sensors, the plurality of capacitive pressure sensors including at least one structured dielectric
Data Source
AI summary
A hypertonicity measuring device comprises at least one wearable item. The hypertonicity measuring device comprises at least one communication pathway. The at least one communication pathway is configured to communicate with a processing device. The hypertonicity measuring device comprises a sensor array. The sensor array is disposed to the at least one wearable item. The sensor array comprises a plurality of capacitive pressure sensors. The sensor array is configured to communicate capacitive pressure sensor data to the processing device employing the at least one communication pathway. The plurality of capacitive pressure sensors comprises at least one structured dielectric. The hypertonicity measuring device comprises an inertial measurement unit. The inertial measurement unit is disposed to the at least one wearable item. The inertial measurement unit is configured to communicate motion data to the processing device employing the at least one communication pathway.